Even now bitcoin's slowly losing its grip as the number 1 coin on the ecosystem, with better and more scalable tokens slowly climbing up the ladder to take its place.
Which one? Solana? 
Solana is valued only 50% of its ATH in 2021 (about $260). It's network stops working regularly for hours, which is much worse than Bitcoin's congestion moments. Full nodes have to handle a high throughput, forget it to run one of them on relatively cheap consumer hardware. The whole network is based on a principle similar to SPV.
And it's not decentralized. It could be described as distributed as Fastly or Cloudflare are, but entities managed by the founders have a lot of control over the network due to the enormous premine.
Basically Solana is a PoS version of BSV. Same is true for XRP and Tron. And all other "platforms" have either a much smaller "real" data throughput than Bitcoin (coins like LTC, BCH/BSV or Doge) or a similar fee problem than Bitcoin (Ethereum, Avalanche).
By the way, Bitcoin's "dominance" value, even if it's a highly flawed indicator, is steady over 50% according to Coingecko. Thus I don't know what you're talking about.
And yes, scalability is important but all these coins employ basically the "big blocks" paradigm and it doesn't solve scalability as long as all transactions have to be processed by all full nodes. The goal of scalability solutions is to bundle several transactions moving them partly off-chain or to alternative chains (sidechains/rollups) where only a part of the nodes have to process them. And in addition, as written in my previous post, it can solve the long term security problem providing a "tail emission" if implemented intelligently via merged-mining.